One Rep Max Calculator
Train with percentages of a real target.
One Rep Max Calculator
Epley: 1RM = Weight x (1 + Reps / 30)
Calculated instantly
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What This Calculator Does
The One Rep Max Calculator estimates your maximum single-repetition lift from a heavier set of several reps. Strength athletes use it to set training loads without attempting a risky true max.
How It Works
The Epley formula estimates 1RM as weight x (1 + reps / 30). The tool also converts to kilograms and reports a common 80% training weight for programming.
Example
Lifting 135 lb for 8 reps estimates a 1RM of 135 x (1 + 8/30) = 171 lb.
Formula
1RM = Weight × (1 + Reps / 30)The Epley formula, most accurate for 1–10 reps.
Reading the Results
Estimated 1 Rep Max
Your projected single-rep maximum derived from the set you completed, used to set training loads.
80% Training Weight
A common working weight for strength sets, calculated as 80% of the estimated max.
Frequently Asked Questions
What is the Epley formula?
It estimates one-rep max as weight multiplied by (1 + reps/30). It is one of the most accurate simple predictors for moderate rep ranges.
Should I test my true 1RM?
Testing a true max carries injury risk. Estimates like this let you program without it, reserving true tests for competitions.
What percentages should I train at?
Strength work commonly uses 70-85% of 1RM, hypertrophy around 65-80%, and power work with low reps at higher percentages.